Field of the Invention
The present invention relates to a needle assembly and, more particularly, to a shieldable blood collection needle assembly.
Description of Related Art
Needle assemblies are used for collecting specimens of fluid, such as blood, from a patient. Some such needle assemblies are intended for use with an evacuated tube and include a housing with a proximal end, a distal end, and a passage extending between the ends. Such needle assemblies further include at least one needle cannula mounted to the housing. The needle cannula includes a sharply pointed distal end that projects distally beyond the housing, a proximal end that projects proximally beyond the housing, and a lumen that provides communication between the opposed ends of the needle cannula. Some needle assemblies include separate proximal and distal cannulas and rely upon a portion of the housing to provide communication between the lumens of the respective cannulas. The distal end of the needle cannula typically is beveled to a tip that is sufficiently sharp for piercing the skin of the patient and accessing the vein or other source of fluid that is to be collected. The proximal end of the needle cannula is configured for piercing the rubber stopper on an evacuated tube. The proximal end of the needle cannula typically is covered by a needle pierceable resealable multi-sample sleeve. The sleeve is compressed by the rubber stopper of the evacuated tube and punctured by the proximal end of the needle cannula as the proximal end of the needle cannula is urged into communication with the evacuated tube. The evacuated tube is typically received by a needle holder secured to the proximal end of the housing.
Prior to use, the needle assembly also typically includes an IV shield and a non-patient shield mounted respectively over the distal end of the needle cannula and the proximal end of the needle cannula. The IV shield and the non-patient shield are frictionally retained on the housing and can be separated through axial movement of the shields away from the housing. The combined needle assembly and evacuated tube is employed by initially urging the pointed distal end of the needle cannula into a blood vessel of a patient. Once the targeted blood vessel has been accessed, the evacuated tube is urged into the needle holder such that the proximal point of the needle cannula pierces the septum of the tube. Low pressure conditions within the evacuated tube, as well as the patient's own vasculature pressure, generate a flow of blood from the patient through the needle cannula and into the evacuated tube. The evacuated tube may be removed from the needle holder after a sufficient quantity of blood has been collected. One or more additional evacuated tubes may similarly be urged into the open end of the needle holder for drawing one or more additional samples of blood to be analyzed. The needle cannula is then withdrawn from the patient after a sufficient volume of blood has been collected for the required analytical procedure.
Many fluid collection needle assemblies are provided with a flashback chamber that communicates with the needle cannula. The flashback chamber typically is formed at least partly from a transparent or translucent material and is intended to receive a portion of the blood flow shortly after a vein has been accessed properly. The flashback chamber gives a positive indication of venous entry after a vein is entered with the distal end of the needle cannula.
In order to reduce the risk of an accidental needle stick, or contact that could transmit pathogens from the patient to the medical practitioner, the needle cannula is shielded after contact with the patient. Shields have taken many different forms. For example, some shields telescope over the needle cannula and frictionally engage the housing. Other shields are telescoped over the housing and can be moved distally over the needle cannula to effect shielding. Other shields are hingedly mounted to or near the housing and can be rotated from an open position, where the needle cannula is exposed, to a closed position, where the needle cannula is shielded.